Digital broadcasting transmission/reception system utilizing mull packet and trs code to improve receiving performance and signal processing method thereof

ABSTRACT

A digital broadcasting transmission and/or reception system having an improved reception performance and a signal-processing method thereof. A digital broadcasting transmitter comprises a TRS encoder for to TRS-encode a MPEG-2 transmission stream having null data for inserting a Known data and a TRS parity at predetermined positions, randomizer to input and randomize data stream from the TRS encoder, a null packet exchanger to replace the null data for inserting the Known data to the known data, and an encoder for encoding a data streams to which the Known data is inserted. Accordingly, the present invention detects the known data from a signal received from a reception side and uses the detected known data for synchronization and equalization and further uses the TRS parity for correcting error of the received signal, so that the digital broadcasting reception performance can be improved at poor multipath channels.

TECHNICAL FIELD

The present invention relates to a digital broadcastingtransmission/reception system, and more specifically, to a digitalbroadcasting transmission/reception system transmitting predefined knowndata with a supplementary reference signal (SRS) added to an MovingPicture Experts Group-2 transport stream (MPEG-2 TS) to improveperformance of a reception system and utilizing a transversal ReedSolomon (TRS) code to reinforce error-correcting capacity and a signalprocessing method thereof.

BACKGROUND ART

The Advanced Television Systems Committee Vestigial Sideband (ATSC VSB)method, a U.S.-oriented terrestrial waves digital broadcasting system,is a single carrier method and uses a field sync by 312 segment unit.Accordingly, reception performance is not good at poor channels,especially at a doppler fading channel.

FIG. 1 is a block diagram of a transmitter/receiver of a generalU.S.-oriented terrestrial waves digital broadcasting system according tothe ATSC digital television (DTV) standards.

The digital broadcasting transmitter of FIG. 1 has a randomizer (110)for randomizing an MPEG-2 TS, an Reed-Solomon (RS) encoder (120) of aconcatenated coder form for adding a parity byte to the TS to correcterrors generated by channel characteristics on transmission, aninterleaver (130) for interleaving the RS encoded data in a certainpattern, and a 2/3 rate Trellis encoder (140) for performing 2/3 rateTrellis encoding and 8 level symbol mapping of the interleaved data, sothat error-correcting encoding of the MPEG-2 TS is performed.

Further, the digital broadcasting transmitter has a multiplexer (150)for inserting a field sync and segment sync in the error-correctingencoded data as a data format of FIG. 2. and a modulator (160) foradding a certain DigiCipher (DC) value to the data symbol inserted withthe segment sync and field sync, inserting a pilot tone therein,performing pulse-shaping and vestigial sideband (VSB) modulation,up-converting them into a signal of RF channel band and transmittingthem.

Accordingly, the digital broadcasting transmitter randomizes the MPEG-2TS through the randomizer (110), the randomized data are outer-codedthrough the RS encoder (120) which is an outer coder, and theouter-coded data are dispersed through the interleaver (130). Inaddition, the interleaved data are inner-coded by 12 symbol unit throughthe Trellis encoder (140) and the inner-coded data are mapped with a 8level symbol, inserted with the field sync and segment sync, insertedwith the pilot tone, VSB-modulated, up-converted into a RF signal andtransmitted.

Meanwhile, the digital broadcasting receiver of FIG. 1 has a tuner (notshown) for down-converting the RF signal received through a channel intoa basic signal, a de-modulator (210) for performing sync detection anddemodulation of the down-converted basic signal, an equalizer (220) forcompensating channel distortion which is generated by multipath in thedemodulated signal, a Viterbi decoder (230) for correcting errors in theequalized signal and decoding the signal in symbol data, a deinterleaver(240) for rearranging the data dipersed by the interleaver (130) of thedigital broadcasting transmitter, an RS decoder (250) for correctingerrors and a derandomizer (260) for derandomizing the data correctedthrough the RS decoder (250) and outputting the MPEG-2 TS.

Accordingly, the digital broadcasting receiver of FIG. 1 down-convertsthe RF signal into baseband, demodulates and equalizes thedown-converted signal, performs channel decoding, and restores theoriginal signal in a reverse order of the digital broadcastingtransmitter.

FIG. 2 shows a vestigial sideband (VSB) data frame of the U.S.-orienteddigital broadcasting (8-VSB) system which is inserted with the segmentsync and field sync. As shown in FIG. 2, one frame consists of twofields and one field consists of one field sync segment which is thefirst segment and 312 data segments. Further, one segment of VSB dataframe corresponds to one MPEG-2 packet and consists of a segment sync offour symbols and 828 data symbols.

In FIG. 2, the segment sync and field sync are used for synchronizationand equalization in the digital broadcasting receiver. That is, thesegment sync and field sync are already known data between the digitalbroadcasting transmitter and receiver and are used as a reference signalon equalization of the receiver.

The VSB method of the U.S.-oriented terrestrial waves digitalbroadcasting system as shown in FIG. 1 is a single carrier method and isweak in a multipath fading channel environment. Accordingly, performanceof a receiver depends on performance of an equalizer to removemultipath.

However, according to the conventional transmission frame as shown inFIG. 2, as a field sync which is a reference signal of the equalizerappears every 313 segment, the frequency of the field sync is lowcompared with a signal of one frame so that equalization performancedecreases.

In other words, it is not easy to estimate a channel, remove multipath,and equalize a received signal using the conventional equalizer and theabove mentioned known data of small quantity. Accordingly, theconventional digital broadcasting receiver has low reception performancein a poor channel environment, especially, in the Doppler fading channelenvironment.

Additionally, the VSB method of the U.S.-oriented terrestrial wavesdigital television system of FIG. 1 is a single carrier system and hasthe low capacity to remove multipath in the Doppler multipath fadingchannel. However, if the known sequence such as a field sync is used alot, the channel is easily estimated and the equalizer easilycompensated the signal distorted by multipath using the known sequence.

However, as shown in the VSB data frame of the U.S.-oriented terrestrialwaves digital television system of FIG. 2, a field sync which is knowndata appears every 313 segment. This is so small quantity, so that thecapacity to remove the multipath by using this decreases. Especially,the capacity to remove multipath in the Doppler multipath fadingchannels is low.

DISCLOSURE OF INVENTION Technical Problem

An aspect of the present invention is to provide a digital broadcastingtransmission/reception system which insert a null packet withoutinformation at certain intervals in an MPEG-2 packet to improvereception performance of the U.S.-oriented terrestrial waves digitaltelevision system of the VSB method, transmit known data and add TRScode so that the receiver detects and uses the known data, and moreefficiently corrects errors by the TRS code to improve receptionperformance and a signal processing, method thereof.

Technical Solution

To achieve the above aspect, a digital broadcasting transmitteraccording to the present invention includes a TRS encoder for receivingan MPEG-2 TS and performing TRS encoding of the MPEG-2 TS, the MPEG-2 TSincluding null data to insert known data and TRS parity respectively ata certain location, randomizer for randomizing the data output from theTRS encoder, a null package replacer for replacing the null data toinsert the known data of the randomized data with the known data, an RSencoder for RS-encoding the data output from the null packet replacerreplacing part and adding an RS parity, an interleaver for interleavingthe data output from the RS encoder, a Trellis encoder forTrellis-encoding the data output from the interleaver, and a modulatorfor modulating the data output from the Trellis encoder, performing RFconverting and transmitting the resultant data.

Preferably, the null data to insert the known data are constructed of acertain number of segments.

Further, the data stream has the information on the insertion locationand the amount of the null data, and the information is inserted priorto the location where the null data are inserted.

More preferably, the digital broadcasting transmitter further includes acontrol signal generator for generating a control signal to control thenull packet replacer to insert the known data at the location accordingto the information.

Further, the Trellis encoder has a memory element for Trellis encodingoperation, initializes the memory element at the location where theknown data are inserted and performs Trellis encoding.

Preferably, the digital broadcasting transmitter further includes apacket buffer for receiving and storing the data which are output fromthe RS encoder and which correspond to the location where the memoryelement of the Trellis encoder is initialized.

The packet buffer receives the data altered according to theinitialization of the memory element from the Trellis encoder.

Further, the digital broadcasting transmitter further includes a parityreplacer for RS-encoding the altered data, which are input from thepacket buffer, according to the initialization of the memory element,generating and outputting an altered RS parity to the Trellis encoder,so that the RS parity added by the RS encoder is replaced by the alteredRS parity.

Additionally, the TRS encoder includes a buffer for storing data inputin the row direction and outputting the data in the column direction, anencoder for TRS encoding the data output from the buffer and adding theTRS parity in the column direction, and a memory for receiving andstoring the data added with the TRS parity and outputting the data inthe row direction.

Meanwhile, a signal processing method for a digital broadcastingtransmitter according to the present invention includes a TRS encodingstep of receiving an MPEG-2 TS and performing TRS encoding of the MPEG-2TS, the MPEG-2 TS including null data to insert known data and TRSparity respectively at a certain location, a randomizing step ofrandomizing the data output from the TRS encoding step, a null packetreplacing step of replacing the null data of the randomized data toinsert the known data with the known data, an RS encoding step ofRS-encoding the data output from the null packet replacing step andadding RS parity, a interleaving step of interleaving the data outputfrom the RS encoding step, a Trellis encoding step of Trellis-encodingthe data output from the interleaving step, and a step of modulating thedata output from the Trellis encoding step, performing RF converting andtransmitting the resultant data.

A digital broadcasting receiver according to the present inventioncorresponding to the digital broadcasting transmitter has a demodulatorfor receiving a signal from the digital broadcasting transmitter anddemodulating the received signal, the signal being inserted with SRS andTRS parity at a certain location, a known data output part for detectingthe location of the SRS from the demodulated signal and outputting theSRS, a equalizer for equalizing the demodulated signal, a Viterbidecoder for error-correcting and decoding the equalized signal using theoutput SRS, a deinterleaver for deinterleaving the data output from theViterbi decoder, a derandomizer for de-randomizing the data output fromthe deinterleaver, and a TRS decoder for TRS-decoding the data outputfrom the derandomizer using the TRS parity.

Preferably, the known data output part includes a known data detectorfor detecting the information on the certain location and an amount ofthe inserted SRS from the received signal, a segment flag generator forgenerating a data frame including at least one segment which indicatesthe location with a predetermined flag, a Trellis interleaver forencoding the data frame as encoded in the digital broadcastingtransmitter, and a known data extractor for extracting and outputtingthe SRS at the location marked with the flag of the encoded data frame.

Additionally, the TRS decoder includes a buffer for storing data inputin the row direction and outputting the data in the column direction, adecoder for TRS-decoding the data output from the buffer using the TRSparity, and a memory for receiving and storing the TRS-decoded data andoutputting the data in the row direction.

Furthermore, a signal processing method for a digital broadcastingreceiver according to the present invention includes a step of receivinga signal from the digital broadcasting transmitter and demodulating thereceived signal, the signal being inserted with SRS and TRS parity at acertain location, a step of detecting the location of the SRS from thedemodulated signal and outputting the SRS, a step of equalizing thedemodulated signal, a step of error-correcting and decoding theequalized signal using the output SRS, a step of deinterleaving thedecoded data, a step of derandomizing the deinterleaved data, and a stepof TRS-decoding the derandomized data using the TRS parity.

ADVANTAGEOUS EFFECTS

According to the present invention, to improve reception performance ofthe ATSC VSB system of the U.S.-oriented terrestrial waves digitaltelevision system, an MPEG-2 packet is inserted with a null packet atcertain intervals, transmitted in known data, and added with TRS code sothat reception performance is improved and reception range can beextended due to low required Signal to Noise Ratio (SNR). Additionally,there is compatibility with the conventional system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a general digital broadcasting (ATSC VSB)transmitter/receiver,

FIG. 2 is a view showing a frame structure of ATSC VSB data,

FIG. 3 is a block diagram of a digital broadcasting transmitter/receiveraccording to the present invention,

FIG. 4 is a view showing a format of TRS input data added with null dataaccording to the present invention,

FIG. 5 is a view showing a format of the data output from a TRS encoder,

FIG. 6 is a view showing a format of data output from a null packetreplacer,

*FIG. 7 is a view showing a format of data output from a parityreplacer,

FIG. 8 is a view showing a format of data output from a datainterleaver,

FIG. 9 is a detailed block diagram of a TRS encoder and decoder, and

FIG. 10 is a block diagram of a known data output part.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention is described in detail referring toaccompanying drawings.

FIG. 3 is a block diagram of a digital broadcasting transmitter/receiveraccording to the present invention.

In FIG. 3, a TS which is input to the digital broadcasting transmitteris inserted with null data to generate a SRS, which is predefined knowndata between the transmitter and the receiver, and TRS code parity andthis will be described in detail later.

The digital broadcasting transmitter includes a TRS encoder (300) foradding RS parity in the column direction, a randomizer (310) forrandomizing the data, a null packet replacer (315) for replacing nulldata packet of the randomized data with a SRS, an RS encoder (320) foradding a RS parity in the row direction, a packet buffer (325) forstoring the RS encoded SRS in memory initialization of a Trellis encoder(340) and replacing it with a altered value according to initialization,a parity replacer (335) for RS encoding again using the altered value,generating a parity, and inputting the generated parity to the Trellisencoder (340), an interleaver (330) for interleaving the RS encodeddata, the Trellis encoder (340) for converting the interleaved data intosymbol and performing 2/3 rate Trellis encoding and symbol mapping, amultiplexer (350) for inserting a field sync and segment sync as a dataformat of FIG. 2, and a modulator (360) for inserting a pilot,performing VSB modulation, RF converting and transmitting the data.Additionally, the digital broadcasting transmitter further includes acontrol signal generator (370) for generating a signal to control thenull data packet and a normal packet including payload data.

FIG. 4 shows a data format of a MPEG-2 TS input to a digitalbroadcasting transmitter according to the present invention.

Referring to FIG. 4, one field of the MPEG-2 TS according to the presentinvention consists of 312 segments with a header having a sync of thefirst byte and packet identity (PID) of the next three bytes. The firstcertain segments of a field are inserted with null data for the SRS inpayload data part, and certain segments at the bottom of the field areinserted with null data for the TRS.

The TRS encoder (300) performs RS encoding of the MPEG-2 TS input to thedigital broadcasting transmitter in the column direction and adds RSparity, which is generated in the column direction, at the location ofnull data inserted in the input TS to generate TRS parity.

FIG. 5 shows a format of the data output from the TRS encoder (300).Referring to FIG. 5, TRS parity generated by the TRS encoder (300) isadded to the location where the null data for TRS are inserted in thedata format of FIG. 4.

The randomizer (310) randomizes the input MPEG-2 TS data to increaseapplication of the allocated channel space.

The null packet replacer (315) generates a particular sequence(Hereinafter, referred to as a known data) of a certain pattern whichare predefined between the transmitter and the receiver as a SRS,replaces the randomized data of the location of the null data for SRS inthe randomized data and inserts the generated known data therein. Thepattern of the known data is different from that of transmitted/receivedpayload data and the SRS is easily detected from the payload data totransmit so that the SRS is utilized for synchronization andequalization of the receiver.

The RS encoder (320) RS encodes the packet data to correct errors by achannel and adds parity of certain bytes.

FIG. 6 shows a format of the data output from the RS encoder (320).Referring to FIG. 6, the null data for the SRS are replaced with theknown data of the particular sequence by the null packet replacer (315)and RS parity is added by RS encoding.

The interleaver (330) interleaves the parity-added packet output fromthe RS encoder (320) in a certain pattern.

The Trellis encoder (340) converts the data output from the interleaver(330) with a symbol and performs symbol mapping through 2/3 rate Trellisencoding. The Trellis encoder (340) initializes a value which istemporarily stored in its own memory element at the beginning locationof the known data and Trellis-encodes the known data.

The packet buffer (325) outputs and temporarily stores the data from thebeginning location of the data corresponding to the location of theknown data from the packet output from the RS encoder (320). Then, whenthe data are Trellis-encoded according to the initialization of theTrellis encoder (340), the packet buffer (325) receives a certain amountof the altered data from the Trellis encoder (340), replaces theprevious data which are temporarily stored, temporarily stores thealtered data and inputs the altered data to the parity replacer (335) toreplace the parity.

The parity replacer (335) receives the data altered according to thememory initialization, regenerates a parity according to the altereddata, and inputs it to the Trellis encoder (340) so that the previousparity is replaced with the regenerated parity.

FIG. 7 shows a format of the data replaced and added with the parityregenerated and output from the parity replacer (335) on the dataaltered according to the Trellis initialization of the data output fromthe RS encoder (320).

Therefore, the packet data output from the Trellis encoder (340) to themultiplexer (350) has a format of the data altered according to thememory element initialization of the Trellis encoder (340) and dataadded with the RS parity according to RS encoding.

FIG. 8 shows a format of the data output from the interleaver (330), andindicates where data for the SRS are located and the location of the RSparity.

Referring to FIG. 8, the corresponding RS parity is located after thedata for SRS. Accordingly, when the Trellis encoder (340) sequentiallyencodes the data input from the interleaver (330) and finishes dataencoding for SRS, the parity for this is replaced with the alteredparity output from the parity replacer (335) and encoded so thatencoding is sequentially performed.

The multiplexer (350) inserts a segment sync in a segment unit and afield sync in a field unit in the data which are converted into symbolby the Trellis encoder (340) as the data format of FIG. 2, adds acertain DC value to a data signal of a certain level and inserts a pilotsignal in edge part of low frequency band on frequency spectrum.

The modulator (360) performs pulse shaping of the signal which isinserted with the pilot signal, loads it on intermediate frequencycarrier wave and modulates amplitude for VSB modulation. Then, themodulated signal is converted into RF, amplified and transmitted througha channel allocated in a certain band.

The control signal generator (370) receives the TS added with null datafrom the randomizer (310), detects the information on the location wherethe null data are added from the TS, generates a control signal torecognize the beginning location and ending location, and inputs it tothe null packet replacer (315), the interleaver (320) and the Trellisencoder (340).

Meanwhile, the digital broadcasting receiver according to the presentinvention follows a reverse order of the transmitter and includes ademodulator (410) for lowering the RF signal to baseband anddemodulating it, an equalizer (420) for deleting inter-symbolinterference, a Viterbi decoder (430) for error-correcting and decoding,a deinterleaver (440), an RS decoder (450), a derandomizer (460), a TRSdecoder (470) and a known data output part (480) for detecting andoutputting the location of the known data.

The demodulator (410) detects and demodulates the sync according to thepilot signal and sync inserted in the baseband signal of the receivedsignal. In addition, the equalizer (420) compensates channel distortionby multipath of a channel from the de-modulated signal and deletes thereceived inter-symbol interference.

The Viterbi decoder (430) corrects errors, decodes the error-correctedsymbol and outputs the symbol data. The decoded data rearranges thedispersed data through the deinterleaver (440).

The deinterleaved data are error-corrected through the RS decoder (450)and the error-corrected data are derandomized through the derandomizer(460).

The TRS decoder (470) corrects errors using the RS parity added in thecolumn direction so that the data of MPEG-2 TS are restored.

FIG. 9 shows a detailed block diagram of the TRS encoder (300) and TRSdecoder (470) according to the present invention.

The TRS encoder (300) includes a buffer (301) for storing the data inputin the row direction and outputting the data in the column direction, anencoder (303) for TRS-encoding the data input in the column directionfrom the buffer and adding parity in the column direction and a memory(305) for receiving and storing the data added with parity in the columndirection and outputting them in the row direction.

Additionally, the TRS decoder (470) has a buffer (471) for storing thedata input in the row direction and outputting them in the columndirection, a decoder (473) for error-correcting the data input in thecolumn direction from the buffer (471) using the RS parity added in thecolumn direction, a memory (475) for storing the error-corrected dataand outputting them in the row direction.

Meanwhile, the known data output part (480) detects the information onthe location of the known data from the demodulated data, generatessegment frame, performs encoding and outputs the generated known data,and provides them to detect sync of the demodulation (410) andcompensate channel distortion of the equalizer (420).

FIG. 10 shows a detailed block diagram of the known data output part(480).

In FIG. 10, the known data output part (480) includes a known datadetector (481), a segment flag generator (483), a Trellis interleaver(485), and a known data extractor (487).

The known data detector (481) detects the quantity information of nullpacket inserted in the reserved part of field sync data segment sectionof the demodulated data and acquires the information on the location andlength of the known data.

According to the detected information on the quantity of the nullpacket, that is, the information on the location and length of the knowndata, the segment flag generator (483) marks with a predetermined flagof length corresponding to the number of data symbols at thecorresponding location and generates at least one segment and a MPEG-2transmission frame including the segment.

The Trellis interleaver (485) encodes the transmission frame generatedin the segment flag generator (483) as encoded in the transmitter, andcan detect the known data according to the flag.

Therefore, the known data extractor (487) acquires the information onthe location which is detected by the flag of the transmission frameswhich are encoded and output from the Trellis interleaver (485), andextracts and outputs the known data at the corresponding location.

According to the present invention, in order to improve receptionperformance of VSB method of the U.S.-oriented terrestrial waves digitaltelevision system, a null packet without information are inserted atcertain intervals in an MPEG-2 packet, known symbol data are transmittedfrom the transmitter using them, a TRS code is added, the receiverdetects and uses the known symbol data, and error-correcting isperformed again using the TRS codes so that reception performance can beimproved at poor multipath channels.

Moreover, SNR to meet TOV can be lowered using TRS codes. This proposedmethod guarantees compatibility with the existing receiver which theATSC proposed and system performance can be improved without performancedegradation of the existing receiver.

Accordingly, reception performance of ATSC VSB method, the U.S.-orientedterrestrial waves DTV system, according to the present invention can beenhanced.

1. A digital broadcast receiver, comprising: a demodulator to receive atransport stream (TS) and demodulate the received TS; an equalizer toequalize the demodulated TS; a known data output part to detect knowndata from the TS and output the detected known data to at least one ofthe demodulator and the equalizer; and a transversal Reed Solomon (TRS)decoder to TRS-decode the TS, wherein the TS is received from a digitalbroadcast transmitter, which comprises a trellis encoder to reset amemory to process the known data, and a parity replacer to performcompensation on an RS parity according to the memory reset, and the TSis generated by the digital broadcast transmitter inserting the knowndata and an RS parity encoded in the column direction into a null dataarea.
 2. The digital broadcast receiver of claim 1, wherein the TRSdecoder performs error correction on the TS using the RS parity added inthe column direction in the TS.
 3. The digital broadcast receiver ofclaim 1, wherein the TRS decoder comprises: a buffer to store data inputin the row direction and output the data in the column direction; adecoder to perform error correction on the data output in the columndirection from the buffer using the RS parity added in the columndirection; and a memory to store the error-corrected data and output thedata in the row direction.
 4. The digital broadcast receiver of claim 1,wherein the known data output part detects information regarding theknown data from the TS demodulated by the demodulator, and detects theknown data using the detected information.
 5. The digital broadcastreceiver of claim 1, wherein the known data output part comprises: aknown data detector to detect the information regarding the known datafrom the TS demodulated by the demodulator; a segment flag generator togenerate a segment by indicating an identification according to thedetected information, and generate a transport frame containing thegenerated segment; a trellis interleaver to encode the generatedtransport frame to correspond to that of the digital broadcasttransmitter; and a known data extractor to extract the known data fromthe transport frame output from the trellis interleaver according to theidentification.
 6. A stream processing method of a digital broadcastreceiver, the stream processing method comprising: receiving a transportstream (TS) and demodulating the received TS; equalizing the demodulatedTS; detecting known data from the TS; and transversal Reed Solomon(TRS)-decoding the TS, wherein the detected known data is used during atleast one of the demodulating operation and the equalizing operation,wherein the TS is received from a digital broadcast transmitter, whichcomprises a trellis encoder to reset a memory to process the known data,and a parity replacer to perform compensation on an RS parity accordingto the memory reset, and wherein the TS is generated by the digitalbroadcast transmitter inserting the known data and an RS parity encodedin the column direction into a null data area.
 7. The stream processingmethod of claim 6, wherein the TRS-decoding operation comprisesperforming error correction on the TS using the RS parity added in thecolumn direction in the TS.
 8. The stream processing method of claim 6,wherein the TRS-decoding operation further comprises: buffering datainput in the row direction and outputting the data in the columndirection; performing error correction on the data output in the columndirection using the RS parity added in the column direction; andoutputting the error-corrected data in the row direction.
 9. The streamprocessing method of claim 6, wherein the detecting operation comprisesdetecting information regarding the known data from the demodulated TS,and detecting the known data using the detected information.
 10. Thestream processing method of claim 6, wherein the detecting operationfurther comprises: detecting the information regarding the known datafrom the demodulated TS; generating a segment by indicating anidentification according to the detected information, and generating atransport frame containing the generated segment; encoding the generatedtransport frame to correspond to that of the digital broadcasttransmitter; and extracting the known data from the encoded transportframe according to the identification.